Editor's Note: Growing requirements for increased availability of IoT devices coincide with the emergence of cellular technologies well suited for the IoT. For developers, the need has never been more acute for more detailed information about cellular technologies and their application to the IoT. Excerpted from the book, Cellular Internet of Things, this series introduces key concepts and technologies in this arena.

In an earlier series, the authors described the evolving landscape for cellular, its role in the IoT, and technologies for massive machine-type communications (mMTC) and ultra reliable low latency communications (URLLC).

In the previous section we provided an overview of interesting unlicensed wireless connectivity solutions for IoT. In this section we discuss how CIoT solutions differ from unlicensed connectivity solutions and what benefits they can provide. For a further discussion on IoT connectivity options, see also Reference [51].

One of the differentiators of CIoT connectivity is that it decouples connectivity provisioning from the IoT service realization. CIoT is built on the high-level paradigm that an independent operator provides suitable IoT connectivity essentially everywhere where an IoT service shall be realized. This means that when a new IoT services is established, no dedicated effort needs to be put in installing, managing, and operating an IoT connectivity solution. Instead the connectivity is realized via the network of an operator. This is different from unlicensed IoT connectivity solutions. In this case, an installation of a connectivity infrastructure is needed to provide connectivity at the location where the IoT service is to be realized. This comprises installing of base stations or access points, establishing backhaul connectivity, providing authentication, authorization, and accounting (AAA) infrastructure, maintaining and updating the connectivity network with security updates, etc. Furthermore, the connectivity needs to be monitored and managed throughout the lifetime of the IoT service. There is the potential that the total cost of ownership for providing and managing a connectivity infrastructure for a wide range of IoT services is lower than the cost of ownership of separate connectivity solutions per IoT service. This is in particular the case when the IoT service and the participating devices are spread over larger areas and are not confined to limited deployments. From the unlicensed technologies, Sigfox provides an operator model for Sigfox-based end-to-end connectivity, where operators build up a dedicated Sigfox infrastructure and connectivity can be purchased by end users.

One major benefit of CIoT solutions is that they provide a reliable long-term and future proof solution. CIoT is based on global standards with very large industry support by a large number of vendors, network, and service providers. The technology outlook is independent from the outlook of few individual market players; this is in contrast to proprietary technologies, which come with high risk concerning their long-term support. CIoT solutions are embedded into cellular communication networks, which are, and will be, an essential infrastructure for a society. Deployment plans are made over decades and systems are built to be highly reliable according to standards with high availability. CIoT systems are built for a global market and allow roaming over multiple operator networks. CIoT networks have full support for mobility of devices, which can also be handled over larger areas because of the wide area coverage and high availability. The rollout of CIoT capabilities, as well as future updates, takes mainly place as software updates to the installed network infrastructure.

One extremely important benefit of CIoT connectivity is that it provides reliable and predictable service performance also for future operation. CIoT uses dedicated spectrum. Radio resources are managed, interference is coordinated, and full quality of service is supported. Long-term guarantees are challenging to provide for any solution based on unlicensed spectrum. Both mobile broadband services and IoT services are predicted to continue to grow. In particular for IoT devices, an extremely strong growth is predicted to hundreds of billions of communicating devices within a decade. Many of those mobile broadband and IoT services will be using unlicensed spectrum, which means that a significant increase in utilization of unlicensed spectrum can be expected. This will in particular provide challenges to long-range unlicensed technologies as described in Section 9.1.1.2.

CIoT also follows the continuous evolution of cellular network technologies, where new capabilities and features are continuously added to the networks. This evolution is designed for backward compatible operation so that devices that cannot be upgraded to new functionality can continue to operate long-term according to the original capabilities, while new services and devices can simultaneously benefit from newer features.

A disadvantage of CIoT is the cost of licensed spectrum resources. This is a cost, which solutions for unlicensed bands do not need to bear. Another potential disadvantage of CIoT for an IoT service provider can be if the CIoT coverage is insufficient for a specific IoT use case. In this case, extra connectivity and corresponding network build-out may be needed to cover the entire IoT service area. If the additional coverage build-out is needed in few confined areas, such a build-out may be simpler and more flexibly arranged with a dedicated deployment rather than when an operator needs to be involved. One property that unlicensed long-range radio technologies have benefitted from is their fast time to market. Any proprietary technology has a timing benefit over standardized solutions that require harmonization and agreements within an entire industry segment. In case of unlicensed LPWAN versus CIoT, a benefit in time to market of unlicensed LPWAN has existed during the last few years, while the CIoT standards were being developed. As the CIoT standards are now finalized and products become widely available, this benefit of unlicensed LPWAN is disappearing. Instead the benefit shifts toward CIoT deployments, which can reach wide coverage quicker and at lower cost due to the reuse of the installed cellular communication network infrastructure.

The next installment in this series will discuss the choice of CIoT technology choices and comparisons.